Electrical testing on a circuit formed on a semiconductor substrate, a liquid crystal device, and the like is conducted using a tester formed of a probe card having a plurality of contact probes disposed corresponding to the arrangement of the circuit to be tested.
A contact probe requires a leading end with contact capability and a spring with urging capability to ensure the contact with the pattern interconnection that is the subject of testing without damaging the interconnection and that allows repetitive usage.
These elements are conventionally configured with a combination of individual components thereof. Fabrication of a contact probe formed integrally by electroforming is disclosed in, for example, Japanese Patent Laying-Open Nos. 2000-162241 and 11-337575. Such contact probes allow the usage of copper, nickel, aluminum, rhodium, palladium, tungsten, a nickel-cobalt alloy, and the like as the electroforming material.
Japanese Patent Laying-Open No. 9-34286 discloses the technique of forming a fixation belt using, as the substrate, an endless electroforming sheet made from a nickel-manganese alloy containing 0.05–0.6 wt % manganese and having a Micro-Vickers hardness of 450–650 to provide a fixation belt for a photolithography apparatus having high thermal conductivity and rigidity as well as superior heat resistance and fatigue resistance.
Japanese Patent Laying-Open No. 11-44708 discloses a contact probe having a plurality of pattern interconnections formed on a film with the tip protruding therefrom, using a nickel-manganese alloy as the material. This contact probe is composed of a first metal layer formed of a nickel-manganese alloy containing at least 0.05% by weight manganese, and a second metal layer having toughness and conductivity higher than those of the first metal layer. The contact probe has the second metal layer bent outwards partially. The publication teaches that such a contact probe has high hardness and high mechanical strength to allow repetitive usage.
For a contact probe, hardness, elasticity, and abrasion resistance are required as a contact that can be repeatedly used by being urged against a circuit to be tested. The contact probe must also be heat resistant to exhibit sufficient performance even when used under high temperature for application to burn-in testing. In accordance with the techniques disclosed in the aforementioned two publications, selection of the component of the alloy to improve the hardness and heat resistance, coverage by means of different types of material, and microscopic configurations have been employed. However, the hardness of the electroforming material was only 600–700 at most in Micro-Vickers hardness. The abrasion resistance was still not sufficient in view of repetitive scribing that will be conducted as a contact probe.
Thus, there is a limit in improving the hardness of a contact probe formed in one piece by means of electroforming since the hardness of the material of the substrate itself is limited. The need arises for a contact probe that can exhibit sufficient performance in all the aspects of hardness, elasticity, abrasion resistance, and heat resistance.